Stratigraphy - Counting Geological Time

Geology is a scientific discipline of historical importance – not least due to the enormous time scales involved.

Stratigraphic section of the Table of Austria (sedimentary layer episodes)
Detail from: Stratigraphic Chart of Austria (Sedimentary Units)
© Austrian stratigraphic Commission and Commission for the Palaeontological and Stratigraphical Research of Austria Austrian Academy of Sciences

Stratigraphy, the study of chronological sequences of rocks and their spatial relationships, represents a cornerstone of geological research.

Outtake from the middle part of the stone core of an ammonite (decorated in yellow, brown and gray). The twisted shells reminiscent of a snail shell. It gives the impression, as plants or algae were on the stone.
Ammonites are well suited for the stratigraphic classification of the Mesozoic.
© Geological Survey of Austria / Andreas Ortag

Not only the knowledge of absolute age but also the relative position of layers and clear definitions of distinct units, are essential. The “Stratigraphic Chart of Austria” forms the basis on a national level.